Simon, one of two alternating narrators, obsessively pursues a peculiar underground life: in the rambling, overgrown grounds of his sister Audrey's estate, he has for years been digging a secret system of tunnels to provide him with a haven of darkness, seclusion, and spying.

The second narrator is Josh, of gypsy background. A naif, he has unpolished artistic talent. While working at a game booth at a fair he meets up with Mortimer - older, self-assured, and demanding. When Josh takes a job as a gardener at Audrey's home, Mortimer tries to consolidate his bond with Josh.

The two women of the household, Audrey and her distant relative and housekeeper Marion, find Josh's strength and seeming innocence a potent spell. Josh finds himself responding to one of the women, escalating unacknowledged tensions between them. Meanwhile, Simon is worried that Josh will find his underground labyrinth and takes steps to prevent this exposure.

Adding the strangely disturbing Mortimer to the mix leads to an explosive chemistry between the characters that will rip apart and rearrange all their lives.